Because of the controversy surrounding the use of mercury-containing amalgam as a restorative material, there is a need to develop an inexpensive posterior restorative alternative which can be used in place of dental amalgam without sacrificing benefits to the patient. The overall objective of this research is to identify alloy powder and liquid gallium alloy combinations which produce biocompatible, clinically-relevant materials with the chemical and physical properties needed for a dental restoration. Specific aims include: a study of reaction kinetics and mechanisms; physical and mechanical property characterization of clinically relevant materials; thermal stability and corrosion behavior of the alloys; and cytotoxicity of the developed alloys. To achieve these aims, the investigators intend to use SEM/XEDA, WDS, XRD, DTA/DSC, and cell culture techniques. The hypothesis to be tested is that a mixed alloy of an experimental powder without noble metals and a gallium-based liquid alloy can have mechanical strengths and other properties at levels similar to or superior to those of leading high-copper amalgams.